Production of solid carbon dioxide



- Dec. 11, 1934. J R CHAMBERLAlN 1,984,249

PRODUCTION OF SOLID CARBON DIOXIDE I Filed Dec. 16, 1930 Zmventor 5R. @hmbmM/w A (Ittomegs Patented Dec. 11', 934. Q 1,984,249

f UNITED STATES PAT-VENT. OFFICE.

PRODUCTION OF SOLID CARBON DIOXIDE 1 Joseph R. Chamberlain, York, Pa., assignor to York Ice Machinery Corporation, York, Pm, a corporation of Delaware Application December is, 19 30,'Serial No. 502,803 13 Claims. ((162-121) This invention relates to the production ofmatically the arrangement and relation oi the solid carbon dioxide or CO2 snow, and particuseveral circuits. larly tov means for condensing and cooling the In the drawing, carbon dioxide gas from any carbon dioxide prior to expansion thereof in the suitable source is conducted through pipe 10 to expansion or snow chamber. It is axiomatic a suction trap 11 and thence to the intake of that the percentage of snow yield from the ex--v compressor 12 in which the 'gasis compressed pension of liquid CO2 is increased by subtraction to about ninety pounds gage. The compressed of sensible heat of the liquid prior to expansion. gas then passes through an interstage cooler l3, Usually this is done by passing theliquid CO2 preferably water cooled, to a dehumidifier i4 through coolers in heat interchanging relation through which flash gas from the expansion with flash gas from the snow chamber. The chamber is passedand wherein moisture is repressure of the liquid CO2 in the last cooling moved from the gas. From the dehumidifier stage is generally rather high, however, necessithe carbon dioxide is taken to a second stage tating compression of the gasthrough several compressor15 in which the pressure is increased 15 stages. I to approximately four hundred pounds gage. In the present invention the condensation and passed through a second cooler 16, preferably subcooling of the carbon dioxide are effected by water cooled, and then to a drier 1'1, which, in

independent refrigeration circuits, that is, cirthe present instance, is a receivercontaining cuits employing a medium other than flash gas calcium chloride, by which practically all of the from the main circuit. Specifically, the C02 moisture present in the gas is removed.

' gas, after being compressed to a moderately high The compressed and dried gas is now liquepressure, is condensed'in an interchanger in fied in a condenser 18, the condensing medium heat exchanging relation with ammonia evapin the present instance being evaporating liquid orating at a relatively low pressure, after which ammonia. The ammonia circuit will be dethe resulting liquid is subcooled in an interscribed in more detail hereinafter. Having been changer in heat exchanging relation with evapliquefied the carbon dioxide flows to a receiver orating liquid C02 in an auxiliary CO2 circuit, 19, thence through the tubes of a shell and the latter being independent of and notcomtube subcooler 21 to expansion chamber 22, the municating with the main circuit. expansion of the liquefied gas being controlled Ammonia, having arelatively high critical by an expansion valve 23. The shell of subtemperature is condensiblewithin the temperacooler 21 forms the evaporator of an auxiliary ture range of available and normal water sup- CO2 refrigerating circuit, which will be later deply, whereas carbon dioxide, the critical temscribed, while the CO: in the main circuit passes perature of which is relatively low, requires for through the tubesof the subcooler. As the car- 3 condensation a relatively low temperature. The bon dioxide flows from an expansion nozzlein arrangement of the present apparatus is such chamber 22, a.portion thereof solidifies, forming that the condensing load ,is carried entirely by a snow-like substance, while the remainder, or water so that, regardless of the water supply, fiash gas, is returned to the compressor through the condensers and subcooler will function unpipes 24, 25 and 26, the latter two pipes being in der varying and extreme weather conditions. communication with suction trap 11 directly, and

As stated hereinbefore, snow yield is increased indirectly, through dehumidifier '14 respectively. by extracting sensible heat from liquefied car- By means of valves 27, 28 the proportion of hen dioxide in the circuit wherein solidification returned gas'passed to the. suction trap directly, is effected. By employing CO2 in the subcooling and indirectly through the shell of the dehumidcircuit there is obtained a heat exchange in ifier 14, may be controlled.

which temperatures corresponding with those The auxiliary or subcooling C0: circuit comproduced by flashing of the CO: in the snow prises a compressor 29 which takes gas from chamberare attained in the cooling circuit. The suction trap 31 at. about ninety pounds gage and temperature of the liquefied CO2 prior to fiashcompresses 'it to approximately four hundred ification, that is, to the lowest temperature practhrough a water cooled heat interchanger 32 ticable while retaining the CO: in its liquefied and through the tubes of condenser 18' to restate. 'ceiver 33. From the receiver the CO2, now in Reference is had in the following description liquid form, is admitted to suction trap 31 and to the appended drawing illustratingdiagramthe connected shell 21 of the sub-cooler, the

ing is thus reduced substantially to that of solidpounds gage. .i'he compressed gas then flows fiow thereto being regulated by a low-side float valve 34. The liquid CO2 evaporated in the shell of subcooler 21 returns to compressor 29 to be recornpressed.

The condensing circuit is similar to the subcooling circuit. except that, in the present instance, ammonia is employed as the refrigerating medium. Ammonia is compressed by compressor and liquefied in a water cooled condenser 36 from which it flows to receiver 37. The liquefied ammonia, after being admitted to suction trap 38 through a low-side float valve 39, evaporates in the connected evaporator shells of condensers l8 and 18, the resulting drop in temperature being sufficient to liquefy compressed carbon dioxide in the main as well as in the auxi1iary-COz circuits. The evaporated ammonia is returned to compressor 35 for recompression. The condensers 18 and 18 are preferably arranged as shown in the drawing. Each of the condensers is a shell and tube interchanger, the shells being connected by relatively large pipes 40 so that the shells of the condensers are connected to form a single evaporator. The

' CO2 circuits are, obviously, separated, the tubes in the respective condensers communicating with separate headers.

The operation of the apparatus is obvious from the foregoing description. The ammonia circuit is employed to condense CO2 gas at moderately high pressure in both the main and subcooling circuits. The subcooling circuit employs a refrigerating medium operating efiiciently at higher pressure than the ammonia circuit and capable of producing lower temperatures in its evaporator upon expansion. The lastmentioned evaporator forms part of a subcooling interchanger designed to remove a substantial amount of sensible heat from the liquefied CO2 in the main circuit prior toits expansion in the snow chamber, thus insuring a relatively high yield of CO2. snow.

It is apparent that the herein described apparatus has decided advantages in that it is only necessary to compress the carbon dioxide to moderately high pressures, that interchangers are not dependent on the flash gas or circuits bled from the main circuit, and that primary condensation is effected by water, the temperature of which is relatively unimportant. By the last statement is meant that the ammonia circuit uses water for condensing, while the refrigerating mediums employed in the other circuits are liquefied by expansion of the ammonia previously condensed by water.' This arrangement, therefore, provides for efficient cooling of the refrigerants in each circuit, regardless of available water temperatures, it being necessary only to vary the speeds of the compressor to regulate the temperatures in the condensers and subcooler. As a result, there is obtained economical condensation of the'compressed gas and extraction of a substantial portion of the sensible heat of the liquefied carbon dioxide before expansion in the snow chamber.

The apparatus is illustrated diagrammatically and is not intended to limit the relation of the several constituents thereof or restrict the invention to the specific refrigerants referred to in the foregoing description.

What is claimed is:

1. In combination, a main closed refrigeration circuit in which carbon dioxide is circulated and to which additional carbon dioxide is supplied; a second closed refrigeration circuit in which a refrigerant is expanded toextract heat from liquid carbon dioxide in the main circuit; a third closed refrigeration circuit in which a refrigerant is expanded to liquefy compressed gases in said second circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

2. In apparatus for solidifying carbon dioxide, a main closed refrigeration circuit for the carbon dioxide; a second closed refrigeration circuit in which a refrigerant is expanded to extract heat from liquid carbon dioxide in the main circuit; and a third closed refrigeration circuit in which a refrigerant is expanded to liquefy compressed gases in said main and second circuits.

3. In combination, a main closed refrigeration circuit in which carbon dioxide is circulated and to which additional carbon dioxide is supplied; a second closed refrigeration circuit in which carbon dioxide is expanded to extract heat from liquid carbon dioxide in the main circuit; a third closed refrigeration circuit in which a refrigerant is expanded to liquefy compressed gases in said second circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

4.. In combination, a main closed refrigeration circuit in which carbon dioxide is circulated and to which additional carbon dioxide is supplied; a second closed refrigeration circuit in which a refrigerant is expanded to extract heat from liquid carbon dioxide in the main circuit; a third closed refrigeration circuit in which ammonia is expanded to liquefy compressed gases in said second circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

5. In combination, a main closed refrigeration circuit in which carbon dioxide is circulated and to which additional carbon dioxide is supplied; a second closed refrigeration circuit in which carbon dioxide is expanded to extract heat from liquid carbon dioxide in the main circuit; a third closed refrigeration circuit in which ammonia is expanded to liquefy compressed gases in said second circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

6. In an apparatus for solidifying carbon dioxide, a plurality of refrigeration circuits of the compression-condensing-expansion type, one of said circuits containing the carbon dioxide to be solidified, another of said circuits containing carbon dioxide and disposed in heat exchanging relation with liquefied carbon dioxide in said first-mentioned circuit, and a third of said circuits containing ammonia in heat exchanging relation with said other circuits.

.7. In combination, a main refrigeration circuit in which carbon dioxide is circulated and to which additional carbon dioxide is supplied; a second refrigeration circuit in which a refrigerant having a relatively low critical temperature is expanded to extract heat from liquid car bon dioxide in the main circuit; a third refrigeration circuit in which a refrigerant having a relatively high critical temperature is expanded to liquefy compressed gases in said second circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

8. In apparatus for solidifying carbon dioxide,

a main refrigeration circuit for the carbon dioxide; a secondrefrigeration circuit in which a refrigerant havinga relatively low critical temperature is expanded to extract heat from liquid carbon dioxide in the main circuit; and a third refrigeration circuit in which a refrigerant having a relatively high critical temperature is expanded to liquefy compressed gases in said main and second circuits.

9. In combination, a main refrigeration circuit in which carbon dioxide is circulated and to which additional carbon doxide is supplied; a second refrigeration circuit in which a refrigerant condensible by heat exchange with water is expanded to condense carbon dioxide in said main circuit; a third circuit in which a refrigerant condensible by heat exchange with expanded refrigerant in said second circuit is expanded to cool liquefied carbon dioxide in said main circuit; and means for expanding liquefied carbon dioxide in the main circuit to form carbon dioxide snow.

10. In an apparatus for solidifying carbon dioxide, a plurality of refrigeration circuits, each including a compressor, a condenser and an expansion chamber, one of said circuits containing the carbon dioxide to be solidified, a second of said circuits containing a refrigerant having a relatively low critical temperature, and a third of said circuits containing a refrigerant having a relatively high critical temperature, the expansion chamber of said last-mentioned circuit forming part of a heat exchanger through which the refrigerants in said other circuits flow and are liquefied, the expansion chamber of said second-mentioned circuit forming part ofa heat exchanger through which liquefied carbon dioxide in the main circuit flows.

11. The method of solidifying carbon dioxide which comprises the steps of compressing, liquefying, subcooling and expanding the carbon dioxide'to form snow, the compressed carbon dithe latter being condensible by heat exchangewith water, and the subcooling being effected by subjection of the liquefied carbon dioxide to heat exchange with a refrigerant condenslble by heat exchange with said expanded refrigerant.

12. The method of solidifying carbon dioxide which comprises the steps of compressing, liquefying, sub-cooling and expanding the carbon dioxide to form snow, the compressed carbon dioxide being liquefied by subjection thereof to heat exchange with an expanded refrigerant, the latter being condensible by heat exchange with water, and the sub-cooling being effected by subjection of the liquefied carbon dioxide to heat exchange with a refrigerant capable of cooling the liquefied carbon dioxide to substantially its freezing temperature.

13. The process for producing solid carbon dioxide, which comprises compressing carbon dioxide gas, liquefying the compressed gas by cooling, then sub-cooling such liquid under the pressure of compressionand liquefaction, then expanding the sub-cooled liquid to form solid carbon dioxide and flash gas; such sub-cooling being performed by expansion of carbon dioxide gas in an independent refrigerating circuit in which carbon dioxide is repeatedly compressed, liquefied by cooling, and expanded; the cooling for liquefaction in each of the two instances aforesaid being performed by the expansion of a refrigerant having a higher critical temperature than carbon dioxide, in a refrigerating circuit in which said .refrigerant is repeatedly compressed, liquefied by cooling, and expanded.

JOSEPH R. CHAMBERLAIN. 

